Fixes for segfaults when the connection to the metadata gets lost

Set stream RelAccx pages to null pointers if we cannot reload those pages

lib/dtsc.cpp

@@ -1298,6 +1298,8 @@ namespace DTSC{
       streamPage.init(pageName, 0, false, true);
       if (!streamPage.mapped){
         INFO_MSG("Page %s not found", pageName);
+        stream = Util::RelAccX();
+        trackList = Util::RelAccX();
         return true;
       }
       stream = Util::RelAccX(streamPage.mapped, true);

src/input/input.cpp

@@ -846,6 +846,10 @@ namespace Mist{
 
       // unload pages that haven't been used for a while
       removeUnused();
+      if (!M){
+        Util::logExitReason(ER_SHM_LOST, "Lost connection to metadata");
+        break;
+      }
 
       if (M.getLive() && !internalOnly){
         uint64_t currLastUpdate = M.getLastUpdated();

src/input/input_buffer.cpp

@@ -187,6 +187,10 @@ namespace Mist{
   /// Detected issues in string format, or empty string if no issues
   /// ~~~~~~~~~~~~~~~
   void inputBuffer::updateMeta(){
+    if (!M){
+      Util::logExitReason(ER_SHM_LOST, "Lost connection to metadata");
+      return;
+    }
     static bool wentDry = false;
     static uint64_t lastFragCount = 0xFFFFull;
     static uint32_t lastBPS = 0; /*LTS*/
@@ -329,6 +333,9 @@ namespace Mist{
 
   void inputBuffer::removeUnused(){
     meta.reloadReplacedPagesIfNeeded();
+    if (!meta){
+      return;
+    }
     // first remove all tracks that have not been updated for too long
     bool changed = true;
     while (changed){